Quantum networks are expected to be heterogeneous systems, combining distinct qubit platforms, photon wavelengths, and device timescales to achieve scalable, multiuser connectivity. Building and iterating on such systems is costly and slow, motivating hardware-faithful simulations to explore architecture design space and justify implementation decisions. This paper presents a framework for simulating heterogeneous quantum networks based on SeQUeNCe, a discrete-event simulator of quantum networks. We introduce faithful device models for two representative platforms - Ytterbium atoms and superconducting qubits. On top of these models, we implement entanglement generation and entanglement swapping protocols for time-bin encoded photons that account for disparate clock rates and quantum frequency conversion and transducer losses/noise brought by the heterogeneity. Using extensive simulations, we map the rate-fidelity trade space and identify the dominant bottlenecks unique to heterogeneous systems. The models are open source and extensible, enabling reproducible evaluation of future heterogeneous designs and protocols.

Quantum communications have progressed significantly, moving from a theoretical concept to small-scale experiments to recent metropolitan-scale demonstrations. As the technology matures, it is expected to revolutionize quantum computing in much the same way that classical networks revolutionized classical computing. Quantum communications will also enable breakthroughs in quantum sensing, metrology, and other areas. However, scalability has emerged as a major challenge, particularly in terms of the number and heterogeneity of nodes, the distances between nodes, the diversity of applications, and the scale of user demand. This article describes InterQnet, a multidisciplinary project that advances scalable quantum communications through a comprehensive approach that improves devices, error handling, and network architecture. InterQnet has a two-pronged strategy to address scalability challenges: InterQnet-Achieve focuses on practical realizations of heterogeneous quantum networks by building and then integrating first-generation quantum repeaters with error mitigation schemes and centralized automated network control systems. The resulting system will enable quantum communications between two heterogeneous quantum platforms through a third type of platform operating as a repeater node. InterQnet-Scale focuses on a systems study of architectural choices for scalable quantum networks by developing forward-looking models of quantum network devices, advanced error correction schemes, and entanglement protocols. Here, we report our current progress toward achieving our scalability goals.

Great technical advances have been achieved since the first atom-trap trace analysis (ATTA) -based radiokrypton application in Egypt, where 1 Myr old groundwater was discovered. Beyond advances in ATTA measurement capabilities, including reduction in sample size, analysis duration, and analytical uncertainty, major progress has been achieved over the past two decades in the sample collection and preparation techniques. These advances paved the expansion of ATTA-based noble gas applications to many other aquifers worldwide, illuminating the nature and flow pattern of deep groundwater systems. While the potential of this new analytical technique for old groundwater dating is well recognized, another important aspect yet to be examined is the reproducibility of radiokrypton in aquifers over time, i.e., how representative is a discrete groundwater sample, collected at a specific time and location, for the natural groundwater system? The likelihood of a negative answer is increased by flow-field disturbance in aquifers following massive groundwater abstraction. Here, we present repeated 81Kr sampling and measurements in twenty-one sites over Israel, mostly of deep (up to 1 km) wells tapping confined aquifers in the arid to hyperarid Negev desert. The results demonstrate that radiokrypton measurements are indeed reproducible, even in cases where samples were collected as long as nine years apart and from highly productive (∼1 Mm3/yr order) pumping wells. Furthermore, many of the repeated measurements in this study (17 out of the 21 sites) were conducted with different ATTA Instruments in two different laboratories using slightly different sampling, preparation, and analysis techniques, yet with an overall good agreement. The consistency in the ATTA-based 81Kr-dating results over time highlights the robustness of this state-of-the-art technique as a tool to unravel groundwater flow patterns and encourages further applications to many other yet-to-be-explored deep aquifers.

We demonstrate excitation of metastable krypton and xenon beams using a vacuum ultraviolet lamp and directly compare the performance of this method to metastable excitation based on a radiofrequency-driven plasma discharge. In our apparatus, lamp-based metastable excitation outperforms the plasma discharge across a wide range of beam flux values relevant for Atom Trap Trace Analysis (ATTA). Moreover, we do not observe significant degradation in lamp performance after over 160 hours of operation. We find that lamp-based excitation is particularly advantageous at the smallest and largest beam fluxes tested, demonstrating the utility of this approach both for improving krypton ATTA and for enabling the detection of radioactive xenon isotopes using ATTA. Finally, we demonstrate an additional enhancement to lamp-based metastable excitation efficiency and stability by applying an external magnetic field.

Many efforts have been made to illuminate the nature of past hydroclimates in semi-arid and arid regions, where current and future shifts in water availability have enormous consequences on human subsistence. Deep desert aquifers, where groundwater is stored for prolonged periods, might serve as a direct record of major paleo-recharge events. To date, groundwater-based paleoclimate reconstructions have mainly focused on a relatively narrow timescale (up to ∼40 kyr), limited by the relatively short half-life of the widely used radiocarbon (5.73 kyr). Here we demonstrate the usage of deep regional aquifers in the arid southeastern Mediterranean as a hydroclimate archive for earlier Mid-to-Late Pleistocene epochs. State-of-the-art dating tools, primarily the 81Kr radioisotope (t1/2 = 229 kyr), were combined with other atmosphere-derived tracers to illuminate the impact of four distinguishable wetter episodes over the past 400 kyr, with differences in climatic conditions and paleo-recharge locations. Variations in stable water isotope composition suggest moisture transport from more proximal (Mediterranean) and distal (Atlantic) sources to different parts of the region at distinct times. Large variability in the computed noble gas-based recharge temperature (NGT), ranging ~15-30 °C, cannot be explained by climate variations solely, and points to different recharge pathways, including geothermal heating in the deep unsaturated zone and recharge from high-elevation (colder) regions. The obtained groundwater record complements and enhances the interpretation of other terrestrial archives in the arid region, including a contribution of valuable information regarding the moisture source origin as reflected in the deuterium-excess values, which is unattainable from the common practice analysis of calcitic cave deposits. We conclude that similar applications in other deep (hundred-m-order) regional groundwater systems (e.g., the Sahara desert aquifers) can significantly advance our understanding of long-term (up to 1 Myr) paleo-hydroclimate in arid regions, including places where no terrestrial remnants, such as cave, lake, and spring sediments, are available.

Atom Trap Trace Analysis (ATTA) is a highly selective and sensitive atom counting technique based on laser cooling and trapping.It has now been established as a routine tool in the geosciences for radiokrypton dating of ancient groundwater and glacial ice samples on timescales of a few ten thousand to a couple million years.The isotope of interest is the cosmogenic krypton-81 with its half-life of 230,000 years and its isotopic abundance at the parts-per-trillion level in the atmosphere.ATTA has the unique advantage of being able to detect this rare isotope completely free of background from any other isotopes, isobars, or molecular interferences.Here, we will highlight recent advances of the ATTA technique that are aimed towards improving the precision of measured isotope ratios and towards enhancing the sample throughput of an ATTA instrument.The first will particularly help address to resolve apparent age differences at the younger end of the effective dating range, e.g., for samples originating from around the period of the last glacial maximum.These advances will be put in context with precise measurements of the absolute krypton-81 abundance in the atmosphere and the recent realization that underground production of krypton-81 can be significant under certain conditions and needs to be carefully considered.Finally, current sample requirements and specifications for radiokrypton analysis at Argonne's Trace Radioisotope Analysis Center will be discussed.

We demonstrate laser frequency stabilization with at least 6 GHz of offset tunability using an in-phase/quadrature (IQ) modulator to generate electronic sidebands (ESB) on a titanium sapphire laser at 714 nm and we apply this technique to perform isotope shift spectroscopy of 226Ra and 225Ra. By locking the laser to a single resonance of a high finesse optical cavity and adjusting the lock offset, we determine the frequency difference between the magneto-optical trap (MOT) transitions in the two isotopes to be 2630.0 ± 0.3 MHz, a factor of 29 more precise than the previously available data. Using the known value of the hyperfine splitting of the 3P1 level, we calculate the isotope shift for the 1S0 to 3P1 transition to be 2267.0 ± 2.2 MHz, a factor of 8 more precise than the best available value. Our technique could be applied to countless other atomic systems to provide unprecedented precision in isotope shift spectroscopy and other relative frequency comparisons.

In preparation for the 2023 NSAC Long Range Plan (LRP), members of the Nuclear Science community gathered to discuss the current state of, and plans for further leveraging opportunities in, QIST in NP research at the Quantum Information Science for U.S. Nuclear Physics Long Range Planning workshop, held in Santa Fe, New Mexico on January 31 - February 1, 2023. The workshop included 45 in-person participants and 53 remote attendees. The outcome of the workshop identified strategic plans and requirements for the next 5-10 years to advance quantum sensing and quantum simulations within NP, and to develop a diverse quantum-ready workforce. The plans include resolutions endorsed by the participants to address the compelling scientific opportunities at the intersections of NP and QIST. These endorsements are aligned with similar affirmations by the LRP Computational Nuclear Physics and AI/ML Workshop, the Nuclear Structure, Reactions, and Astrophysics LRP Town Hall, and the Fundamental Symmetries, Neutrons, and Neutrinos LRP Town Hall communities.

This whitepaper presents the research priorities decided on by attendees of the 2022 Town Meeting for Fundamental Symmetries, Neutrons and Neutrinos, which took place December 13-15, 2022 in Chapel Hill, NC, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 275 scientists registered for the meeting. The whitepaper makes a number of explicit recommendations and justifies them in detail.

The 53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics will take place from May 30 – June 3, 2022 in Orlando, Fl, USA. Virtual Help Desk

36Cl and 81Kr (half-lives of 301 and 229 kyr, respectively) are among a very few age tracers with dating capabilities in the 104–106 yr timescale. Although widely applied since the 1980s in various hydrological studies, the 36Cl/Cl system has been found complex as an effective dating tool. In contrast, 81Kr has become a practical tool only recently and is considered to be an ideal dating tool due to the inert properties of the noble gas. In the present study, simultaneous measurements of both radioisotopes were used to assess the 36Cl/Cl input ratios and the Cl- content for paleorecharge into the deep, transboundary Nubian Sandstone Aquifer (NSA) which stretches below the hyperarid deserts of the Sinai Peninsula (Egypt) and the Negev (Israel).By means of 81Kr data, reconstructed Cl- content of recharge that occurred during the late Pleistocene was found to be 300–400 mg/L with an initial 36Cl/Cl ratio of 50 × 10-15. This latter value is in agreement with the 36Cl/Cl ratio in recent local rainwater, indicating constancy over prolonged periods with possible variable climatic conditions. This similarity in values suggests a process that is rather insensitive to atmospheric 36Cl fallout rates. Erosion and weathering of near-surface materials in the desert environment could dominate the hydrochemistry of rains, floods, and the consequent groundwater recharge. This near-surface Cl- reservoir integrates various sources and processes, including marine and terrestrial Cl-, cosmogenic 36Cl fallout, and cosmogenic 36Cl production in the shallow unsaturated zone, all of which are active over long timescales and accumulate on the land surface and in the epigene zone. Spatial differences in the reconstructed initial 36Cl/Cl ratio are attributed to differences in the mineral aerosol sources for specific recharge areas of the NSA. The results of this study highlight the potential of integrating 81Kr age information in evaluating the initial 36Cl/Cl and Cl- input, which is essential for the calibration of 36Cl radioisotope as a long-term dating tool for a given basin.

The Ra EDM experiment uses a pair of high voltage electrodes to search for the atomic electric dipole moment of Ra-225. We use identical, plane-parallel electrodes with a primary high gradient surface of 200 mm(2) to generate reversible DC electric fields. Our statistical sensitivity is linearly proportional to the electric field strength in the electrode gap. We adapted surface decontamination and processing techniques from accelerator physics literature to chemical polish and clean a suite of newly fabricated large-grain niobium and grade-2 titanium electrodes. Three pairs of niobium electrodes and one pair of titanium electrodes were discharge conditioned with a custom high voltage test station at electric field strengths as high as +52.5 kV/mm and -51.5 kV/mm over electrode gap sizes ranging from 0.4 mm to 2.5 mm. One pair of large-grain niobium electrodes was discharge-conditioned and validated to operate at +/- 20 kV/mm with steady-state leakage current <= 25 pA (1 sigma) and a polarity-averaged 98 +/- 19 discharges per hour. These electrodes were installed in the Ra EDM experimental apparatus, replacing a copper electrode pair, and were revalidated to +/- 20 kV/mm. The niobium electrodes perform at an electric field strength 3.1 times larger than the legacy copper electrodes and are ultimately limited by the maximum output of our 30 kV bipolar power supply.

Measurements of the long-lived Kr-81 and Cl-36 radioisotopes in groundwater from the Negev Desert (Israel) were used to assess the Cl-36/Cl input ratios and Cl- contents for paleorecharge into the Nubian Sandstone Aquifer (NSA). The reconstructed Cl- content of the recharge flux was on the order of 300-400 mg/L. An initial Cl-36/Cl ratio of 50 x 10(-15) was assessed for the groundwater replenishment in the Negev Desert since the late Pleistocene, in agreement with the Cl-36/Cl ratios in recent local rainwater. This is despite possible changes in the climatic conditions and the Cl-36 production rates in the atmosphere over this timeframe. This similarity in values is explained by the major role played by the erosion and weathering of near-surface materials in the desert environment that dominate the hydrochemistry of rains, floods, and the consequent groundwater recharge. Spatial variation in the reconstructed initial Cl-36/Cl ratio is accounted for by the differences in the mineral aerosol sources for specific recharge areas of the NSA. Accordingly, regional variations in the Cl-36/Cl input in groundwater reservoirs surrounding the Mediterranean Sea indicate various processes that govern the Cl-36/Cl system. Finally, the results of this study highlight the great advantage of integrating Kr-81 age information in evaluating the initial Cl-36/Cl and Cl- input, which is essential for the calibration of Cl-36 radioisotope as an available long-term dating tool for a given basin. (C) 2020 Elsevier B.V. All rights reserved.

We report a method for the precision measurement of the oscillator strengths and the branching fractions of the decay channels of the 6d7p F-3(2)o state in Ra-226. This method exploits a set of metastable states present in Ra, allowing a measurement of the oscillator strengths that does not require knowledge of the number of atoms in the atomic beam. We measure the oscillator strengths and the branching fractions for decays from the 6d7p F-3(2)o state to the 7s6d D-3(1), 7s6d D-3(2), and 7s6d D-1(2) states and constrain the branching fraction to the 7s6d D-3(3) state to be less than 0.4% (68% confidence limit). The lifetime of the F-3(2)o state is determined to be 15 +/- 4 ns.

We report a method for the precision measurement of the oscillator strengths and the branching ratios of the decay channels of the 6d7p F o 2 state in Ra. This method exploits a set of metastable states present in Ra, allowing a measurement of the oscillator strengths that does not require knowledge of the number of atoms in the atomic beam. We measure the oscillator strengths and the branching ratios for decays to the 7s6d D1, 7s6d D2, and 7s6d D2 states and constrain the branching ratio to the 7s6d D3 state to be less than 0.4% (68% confidence limit). The lifetime of the F o 2 state is determined to be 15± 4 ns.

This whitepaper is an outcome of the workshop Intersections between Nuclear Physics and Quantum Information held at Argonne National Laboratory on 28-30 March 2018 [www.phy.anl.gov/npqi2018/]. The workshop brought together 116 national and international experts in nuclear physics and quantum information science to explore opportunities for the two fields to collaborate on topics of interest to the U.S. Department of Energy (DOE) Office of Science, Office of Nuclear Physics, and more broadly to U.S. society and industry. The workshop consisted of 22 invited and 10 contributed talks, as well as three panel discussion sessions. Topics discussed included quantum computation, quantum simulation, quantum sensing, nuclear physics detectors, nuclear many-body problem, entanglement at collider energies, and lattice gauge theories.

Optical trapping techniques are an efficient way to probe limited quantities of rare isotopes. In order to achieve the highest possible measurement precision, it is critical to optimize the optical trapping efficiency. This work presents the development of a three-dimensional semi-classical Monte Carlo simulation of the optical trapping process and its application to optimizing the optical trapping efficiency of Radium for use in the search of the permanent electric dipole moment of $^{225}$Ra. The simulation includes an effusive-oven atomic beam source, transverse cooling and Zeeman slowing of an atomic beam, a three-dimensional magneto-optical trap, and additional processes such as collisions with residual gas molecules. We benchmark the simulation against a well-characterized $^{88}$Sr optical trap before applying it to the $^{225}$Ra optical trap. The simulation reproduces the relative gains in optical trapping efficiency measured in both the $^{88}$Sr and $^{225}$Ra optical traps. The measured and simulated values of the overall optical trapping efficiencies for $^{88}$Sr are in agreement; however, they differ by a factor of $30$ for $^{225}$Ra. Studies of several potential imperfections in the apparatus or systematic effects, such as atomic beam source misalignment and laser frequency noise, show only limited effects on the simulated trapping efficiency for $^{225}$Ra. We rule out any one systematic effect as the sole cause of the discrepancy between the simulated and measured $^{225}$Ra optical trapping efficiencies; but, we do expect that a combination of systematic effects contribute to this discrepancy. The accurate relative gains predicted by the simulation prove that it is useful for testing planned upgrades to the apparatus.